This part provides background information related to the present disclosure, which is not necessarily the conventional technology.
With the explosive increase of user data, the requirements for the data transmission rate and the data transmission efficiency are improved, and the communication load between a user and a base station is increased. Under such background, the D2D communication technology has been developed. The D2D communication technology represents an information transmission manner in which cellular communication user equipments directly exchange data in the terminal direct communication way. As compared with the traditional cellular communication technology, the D2D communication technology has features of reusing spectrum resources, having short transmission distances, and transmitting information not via a base station. Therefore, with the D2D communication technology, the spectrum utilization can be increased, the transmitting power of the user equipment and the load of the base station can be reduced, and the signal has a better performance due to the short communication distance, thereby facilitating to reduce the communication interference to other devices.
The D2D communication includes two processes, i.e., a link mutual discovery process and a data transmission process. The discovery process is mainly intended to determine which users are in the vicinity of a user. The discovery process may be performed by two manners including a distributed manner and a centralized manner. In the distributed manner, users automatically select radio resources from a resource pool for signal transmission in the discovery process. In a case that some users close to each other selects the same resource block, a conflict occurs during the signal transmission. In the centralized manner, the resource configuration is performed semi-statically according to the users. The data transmission process is mainly intended to configure resources for D2D links and transmit data via the links. The data transmission process may also be performed by two manners including a distributed manner and a centralized manner. In the distributed manner, the users select resources from the resource pool to transmit data and control information, and a conflict may occur in this manner. In the centralized manner, the resource configuration for the users is performed by the base station to cause the users to transmit data and control information.
The current D2D research mainly focuses on a public safety scenarios. However, the D2D links cannot be only applied in the scenarios. In a dense non-public security scenario, hundreds or thousands of users perform the D2D communication simultaneously via mobile phones or laptops. The requirements of the dense non-public security scenarios are different from those of the public safety scenarios. For the public security scenarios, a high reliability and a low complexity are the most important factors. For the dense non-public security scenarios, it should be ensured that a user can perform convenient and effective D2D communication in a case that many other users exist in the vicinity of the user, that is, the effectiveness and the user capacity are highly required. In the distributed manner and the centralized manner of the data transmission process described above, since a conflict easily occurs in the distributed manner, the centralized manner is more applicable in the dense non-public security scenarios.
In the dense non-public security scenarios, an appropriate scheduling method should be adopted to ensure the effectiveness of the D2D communication and the user capacity. A perfect scheduling method should meet the following two criteria: 1) avoiding that two D2D links that are interfered by each other simultaneously transmit information; and 2) allowing that two D2D links that are not interfered by each other simultaneously transmit information. In order to meet the above criteria, the base station is required to acquire specific information on whether any two D2D links are interfered by each other. In the current research, which D2D links that are not interfered by each other to simultaneously perform the communication can be determined based on the locations of the users, with a geographic location-based scheduling method.
In the geographic location-based scheduling method, a problem how to acquire the specific location information of each user equipment is caused. In a case that a GPS or other similar methods is used, the following problems may be caused. 1) A user is required to be able to acquire its own geographic location information. 2) The base station is required to acquire location information of the user equipment. 3) The location information is not accurate enough in environments such as an indoor environment. 4) The accuracy of the acquired geographic location is in the order of tens of meters, which meets the navigation requirements but is insufficient for scheduling. Therefore, in the geographic location-based scheduling method, it is difficult to accurately acquire the location information of the user equipment, so that the determined D2D links that are interfered by each other and the determined D2D links that are not interfered by each other are not accurate enough, and thus the scheduling performed by the base station is not reasonable enough.
In view of the above technical problems, it is desired to provide a solution to accurately determine the D2D links that are not interfered by each other and the D2D links that are not interfered by each other without acquiring the geographic position of the user equipment, thereby more reasonably configuring resources, and thus improving the effectiveness of the D2D communication and the system capacity.